The present invention is directed to heat sinks in general, and more particularly to heat sinks for use in dissipating waste heat generated by electrical or electronic components and assemblies.
High power electrical and electronic components continue to have an increasing demand for higher power dissipation within a relatively confined space. Ever increasing electronic device speeds and power utilization have thus required continually increased heat dissipation capabilities of the associated heat sinks. In order to provide for such higher power dissipation requirements while remaining suitably compact, several levels of thermal management are usually required at the device, sub-assembly and component level.
At the component level, various types of heat exchangers and heat sinks have been used that apply natural or forced convection or other cooling methods. Some of the cooling solutions utilized for electronics applications include air (natural or forced convection), liquid, and refrigerant cycle apparatuses. One type of prior art heat sink for electrical or electronic components implementing a forced air convection configuration is illustrated in FIG. 1 and shown generally at 10. Heat sink 10 employs a base plate 12 that has a bottom surface 16 to which the electrical device is attached and a top surface 14 from which a plurality of plates 18 extend upwardly defining wherein each adjacent pair of plates defines a space therebetween. The spaces between adjacent plates 18 are populated with convoluted folded fins 24 extending between adjacent plates 18 to define a plurality of substantially horizontal cooling passageways. A fan 28 is mounted at one end to draw or blow air through the cooling passageways to effect heat transfer from the fins 24 to the air drawn therethrough and then expelled from the heat sink 10.
For a given cooling application, the heat sink base footprint is typically fixed by a standard mounting pattern. The surfaces extending from the base and the fans must also fit within the available volume constraints of the same application. Since the base configuration is more or less standardized, performance improvements must then be derived primarily from enhancements to the extended surfaces. Heat transfer limitations in prior art heat sinks have been, in part, caused by:
1. Insufficient extended surface area for forced convection;
2. Insufficient enhancements to the extended surfaces;
3. Non-optimized thermal conduction paths to the extended surfaces; and
4. Poor volume or management of airflow through the extended surfaces.
Thus, what is desired is a heat sink incorporating enhancements to the surfaces extending from the base plate to further improve the efficiency of a heat sink over a given area of the base plate.
One aspect of the present invention is a heat sink for cooling electrical or electronic devices. The heat sink comprises a base plate having a top surface and a bottom surface for attaching to the electronic device. At least two vertical plates are affixed to and extend substantially perpendicularly from the top surface in a spaced apart manner and are parallel one to the other. A secondary fin is affixed to and extends between an upper portion of the vertical plates. The secondary fin has a top convoluted edge and a bottom convoluted edge and is oriented such that the bottom convoluted edge faces the top surface of the base plate. The secondary fin includes a plurality of individual fins formed in a convoluted accordion-like manner. The plurality of individual fins define a plurality of secondary fin passageways between adjacent ones of the individual fins wherein each secondary fin passageway extends from the top convoluted edge to the bottom convoluted edge.
Another aspect of the present invention is a method of cooling an electronic device. The method includes the steps of providing a heat sink of the type comprising a base plate having a top surface and a bottom surface, wherein a plurality of vertical plates are affixed to and extending substantially perpendicularly from the base plate top surface in a parallel spaced apart manner. The heat sink also includes a secondary fin affixed to and extending between an upper portion of each adjacent pair of vertical plates wherein the lower portion of each adjacent pair of vertical plates and the bottom of the secondary fin define a primary passageway at each end of the heat sink above the base plate. The secondary fin has a top edge and a bottom edge and oriented such that the bottom edge faces the base plate top surface. The secondary fin further includes a plurality of individual fins formed in a convoluted accordion-like manner defining a plurality of secondary fin passageways between adjacent ones of the individual fins. The bottom surface of the heat sink is affixed to electronic device, and a fan is attached to a top of the heat sink. The fan is then caused to draw air into the primary passageways and through the plurality of secondary fin passageways.
These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings.